In cardiac surgery, the use of cardiopulmonary bypass may alter the kinetics and plasma concentration of drugs, including antibiotics. On the other hand, infection of the surgical field and/or mediastinitis are serious complications of cardiac surgery, with incidence ranging from 1.9 to 15%, especially when considering the lower limb infections. Inadequate prophylactic antibiotic therapy, besides not preventing infection, it can select resistant microorganisms. The second-generation of cephalosporin antibiotics have been the most used as prophylactic antibiotic for cardiac surgery due to its low toxicity and cost, good tissue penetration, good spectrum of activity against bacterias that often cause postoperative infection, i.e. Staphylococcus aureus and coagulase negative Staphylococcus, which colonize the patients' skin, and Escherichia coli, Klebsiella spp, Enterobacter spp, Proteus spp, and Pseudomonas spp, bacteria common in the lower limb or perineum which may contaminate the chest or the location of the saphenectomy. Regarding cefuroxime, it is important that the plasma concentration four times higher than the MIC (minimal inhibitory concentration), i.e. 16 g/L is maintained throughout the surgical procedure.